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  <a href="http://sudopedia.enjoysudoku.com/ALS-XZ.html">ALS-XZ</a>
  <p>
   Almost Locked Sets (ALS) are groups of N cells in a single house with N+1 candidates (e.g. 3 cells with 4 candidates).<br> 
   The two cell groups <b>{0}</b> and <b>{1}</b> are both <a href="http://sudopedia.enjoysudoku.com/Almost_Locked_Set.html">Almost Locked Sets</a>.
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  <p>
   <b>Digit {4}</b> (the x digit) is <a href="http://sudopedia.enjoysudoku.com/Restricted_common.html">restricted common</a>
    to the two ALSes meaning it cannot be present in both sets at the same time.<br/>
   In any case (first ALS contains {4}, second ALS contains {4}, none of the ALSes contains {4}) one of the ALSes turns into a 
   <a href="http://sudopedia.enjoysudoku.com/Subset.html">Locked Set</a>.<br/>
  </p>
  <p>
   Since both ALS contain <b>digit {5}</b> (the z digit), it gets locked into at least one of the ALSes.
   Therefore one of the ALS cells must contain <b>digit {5}</b> and none of the cells seeing all these ALS cells can contain <b>digit {5}</b> as a candidate.
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